摘要
用 4个恒定温度 ( 2 4～ 32℃ )孵化灰鼠蛇卵 ,检测温度对孵化期、孵化成功率和孵出幼体特征的影响。在 2 4～ 32℃范围内 ,孵化温度显著影响孵化期及孵出幼体的体长和剩余卵黄大小 ,但不影响孵化成功率和孵出幼体的性别、体重、躯干重和脂肪体重。 2 4、2 6、30和 32℃孵化期分别为 99.0、72 .2、5 4 .7和 4 8.7d。 2 4℃和 2 6℃孵出幼体的体长大于 30℃和 32℃孵出幼体 ;2 4℃和 32℃孵出幼体内的剩余卵黄较多。不同温度下发育的胚胎对卵内物质和能量的利用有一定的差异 ,但差异不显著。雌性幼体的体长、尾长和总长均大于雄性幼体 ,这些两性差异与孵化温度无关。孵出幼体和新生卵内容物灰分含量无显著差异 ,孵化前后卵壳灰分含量也无显著差异 ,表明灰鼠蛇的卵黄可提供胚胎发育所需的所有无机物。
The gray rat snake, Ptyas korros (Colubridae), is a kind of popular oviparous snake in the southern provinces of China. Herein, we established an experimental protocol using the gray rate snake as the animal model to examine (1) influence of temperature on hatching success, hatching time, (2) influence of temperature on hatchling traits, (3) influence of temperature on embryonic use of energy and material. In early July 1999, we collected 11 gravid females from a private peddler at Jiande county, Zhejiang province, east China. The females were brought to our laboratory in Hangzhou Normal College, where they were randomly assigned 1～2 to a 50×50×50cm\+3 wire cage placed in an air-conditioned room at 28～30 ℃. Food (frogs) and water were provided libitum. The animals begin to lay eggs a few days after their arrival. Cages were checked for a minimum of six times daily for the presence of eggs so that eggs could be collected, weighed measured promptly. Throughout the reproductive season, A total of 74 freshly laid eggs were collected. We randomly selected one freshly laid egg, which were then dissected and separated into eggshell and egg contents (yolkembryo), from each of the clutches. The embryo was too small and fragile to be separated and therefore was included with the yolk. Egg contents were put into a pre-weighed dish and weighed. Eggshells were rinsed briefly in distilled water, dried by blotting with a paper towel and weighed. Egg contents and eggshells were then oven-dried to constant mass at 65 ℃ for a minimum of 24 h, weighed and stored frozen at -15 ℃ until they could be processed for determining composition. The remain eggs were put into plastic boxes contained moist vermiculite (-220kPa, dry vermiculite : water = 1:1). The boxes were then placed into the incubators whose temperature was set at 24, 26, 30 and 32 ℃, respectively. As soon as possible, eggs from each clutch were equally assigned into the containers at the four above-mentioned temperatures so as to avoid the family effect. Furthermore, we moved the boxes among shelves daily according to a predetermined schedule to minimize any effects of thermal gradients inside the incubator. All containers were weighed daily and, if necessary, water was added to compensate for small evaporative losses, so that the water potential of the substrate was maintained constant. Duration of incubation was defined as the elapse time from egg laying to hatchling emergence. Upon emergence, each hatchling was measured, weighed, killed by freezing to -15 ℃, and then separated into carcass, residual yolk and fat bodies. The three components were oven dried to constant mass at 65 ℃, weighed and preserved frozen for later determination of composition. We extracted non-polar lipids from dried samples in a Soxhlet apparatus for a minimum of 5.5 h using absolute ether as solvent. The amount of lipids in a sample was determined by subtracting the lipid-free dry mass from the total sample dry mass. The total lipid in each hatchling was calculated as the sum of the lipids in its carcass, residual yolk and fat bodies. We determined energy density of dried samples using an adiabatic bomb calorimeter and ash (inorganic material) content in each sample using a muffle furnace at 800 ℃ for a minimum of 8 h and then weighing the remaining ash. All variables were tested for normality using Kolmogorov-Smirnov test and for homogeneity of variance using Bartlett's test prior to further statistical analysis, and all data met the assumption of parametric analyses. We used G-test, two-way analysis of variance (two-way ANOVA) and analysis of covariance (ANCOVA). Homogeneity of slopes was checked prior to testing for differences in adjusted means. For multiple comparisons, we used Tukey's test. Significance level was set at α = 0.05. Within the range from 24 to 32 ℃, temperature significantly affected incubation period of P. korros eggs, which decreased dramatically with increase in incubation temperature. The duration of incubation at 24, 26, 30, and
出处
《生态学报》
CAS
CSCD
北大核心
2002年第4期548-553,共6页
Acta Ecologica Sinica
基金
浙江省自然科学基金青年人才专项基金资助项目
浙江省 1 5 1人才基金资助项目
杭州市跨世纪人才基金资助项目
关键词
孵化温度
灰鼠蛇卵
孵化期
孵化成功率
幼体特征
游蛇科
Colubridae
Ptyas korros
egg
incubation temperature
duration of incubation
hatching success
hatchling traits
